Floral Biology and Breeding System of the Narrow Endemic Dianthus Morisianus Vals

Flora 219 (2016) 1–7 Contents lists available at ScienceDirect Flora journal homepage: www.elsevier.com/locate/flora Floral biology and breeding system of the narrow endemic Dianthus morisianus Vals. (Caryophyllaceae) a a b,∗ a Anna Nebot , Donatella Cogoni , Giuseppe Fenu , Gianluigi Bacchetta a Centro Conservazione Biodiversità (CCB), Dipartimento di Scienze della Vita e dell’Ambiente, Università degli Studi di Cagliari, Viale S. Ignazio da Laconi 11-13, 09123, Cagliari, Italy b Dipartimento di Biologia Ambientale, “Sapienza” Università di Roma, Piazzale A. Moro 5, 00185 Roma, Italy a r t i c l e i n f o a b s t r a c t Article history: Dianthus morisianus Vals. (Caryophyllaceae) is a narrow endemic species of Sardinia, growing with only Received 4 August 2015 one natural population on the Portixeddu coastal dune system (southwest Sardinia). In this work we Received in revised form 9 December 2015 investigated the ex situ phenology and the breeding system through hand-pollination experiments to Accepted 17 December 2015 investigate whether this endemic plant presents inbreeding depression. D. morisianus had a floral lifes- Edited by Stefan Dötterl pan of a week; the maximum flowering moment occurred in June and the cultivated plants presented Available online 21 December 2015 high flowering synchrony. Among several traits measured, there were only differences in fruit set and first leaf appearance between geitonogamous and xenogamous treatments, and we detected differences Keywords: in the number of seeds and first leaf appearance in accordance to the origin of the mother plant (mother Inbreeding depression effect). The plants cultivated ex situ present inbreeding depression only in germination time (T50), and Mediterranean plant Mixed matting system the cumulative inbreeding depression was negligible. D. morisianus is self-compatible and presents fac- Phenology ultative xenogamy as its breeding system. Our data suggest that inbreeding depression should not be Reproductive biology a major issue in D. morisianus. The results of this study are of value for further conservation actions on Self-compatible natural population of this threatened endemic plant. © 2015 Elsevier GmbH. All rights reserved. 1. Introduction Collin et al., 2009). Inbreeding depression is not a fixed state; it can vary depending on which life history stage is most negatively The reproductive biology of a plant affects, at least to some affected (Kittelson and Maron, 2000). Negative effects of inbreeding extent, its reproductive success (Rymer et al., 2005) and can have on reproductive traits and offspring establishment have been doc- important consequences for the viability of its populations (Evans umented in several plant species (Bellanger et al., 2015; Fishman, et al., 2003). Specifically for threatened plants, the reproductive 2001; Sedlacek et al., 2012). biology is of special importance because of its direct effect on pop- In general, outcrossed progeny have higher levels of genetic ulations’ growth, dispersal and colonization (Saunders and Sipes, diversity than those produced by self-fertilization, in which the 2006). It can also provide indirect information related to con- effects of inbreeding depression are observed (Cursach and Rita, servation efforts such as patterns of genetic diversity, threats of 2012; Teixera et al., 2009). However, selfed progeny offers repro- diversity loss, risk of inbreeding depression, and risks associated ductive assurance when pollinators are scarce, or limited pollen with changes in pollinator abundance or effectiveness (Evans et al., transfer reduces the reproductive output (Barret, 1998; Cursach 2003; Menges, 1991; Nell, 2002). and Rita, 2012; Knight et al., 2005). Several studies highlight that Mating patterns are prime determinants of the levels of inbreed- threatened plants exhibit slightly higher levels of self-compatibility ing (Barrett and Kohn, 1991). Inbreeding depression and selfing than common plants (Saunders and Sipes, 2006). rates play important roles in studies describing the evolution The genus Dianthus L. (Caryophyllaceae) is one of the most of plant mating systems (Charlesworth and Charlesworth, 1978; diverse plant genera in Europe and is characterized by several endemic taxa in the Mediterranean region (Valente et al., 2010). In Sardinia, eight endemic taxa of the Dianthus sylvestris Wulf. group have been recorded, and four of them are narrowly dis- ∗ Corresponding author. tributed (Bacchetta et al., 2010). Dianthus morisianus Vals. is the E-mail addresses: [email protected] (A. Nebot), only psammophilous plant of this group in the Mediterranean Basin [email protected] (D. Cogoni), [email protected] (G. Fenu), and grows with only one natural population on the Portixeddu [email protected] (G. Bacchetta). http://dx.doi.org/10.1016/j.flora.2015.12.004 0367-2530/© 2015 Elsevier GmbH. All rights reserved. 2 A. Nebot et al. / Flora 219 (2016) 1–7 Fig. 1. Cultivated plant of Dianthus morisianus (A), flower at male stage (B) and flower at female stage (C). coastal dune system (Buggerru, South–West Sardinia; Bacchetta stigma 14 mm long (Bacchetta et al., 2010; Fig. 1B–C). The flowering et al., 2010). The natural habitat of D. morisianus has been strongly season is from early May to late June, and ripe fruits can be found modified by human activities, causing habitat loss and fragmenta- during June–July (Bacchetta et al., 2010). Seedling emergence rep- tion (Cogoni et al., 2013). The small size of the population and the resents the most critical stage for the long-term persistence of D. limited seedling recruitment make D. morisianus potentially prone morisianus, while the lack of a persistent soil seed bank represents to extinction and, for this reason, this plant is considered as one of a hazard to the persistence of the natural population (Cogoni et al., the most threatened plants on the island (Bacchetta et al., 2012) 2012). and it is categorized as Critically Endangered on the IUCN Global Ripe fruits of D. morisianus were collected in July 2010 from 50 Red Lists (Fenu et al., 2013). In order to reduce the extinction risk, plants growing in the natural population. The seeds were cleaned two experimental translocation programs were realized. The first and stored according to the mother at the Sardinian Germplasm ◦ reintroduction was in a protected and fenced site, while the sec- Bank (BG-SAR) under controlled conditions in a dry room (15 C ond one was in an open and unprotected site. Both these sites are and 15% relative humidity [RH]). In October 2010, 100 seeds from located in areas near to the natural population (Cogoni et al., 2013; 20 different plants (five seeds per plant) were sown in 100 square Fenu et al., 2015). pots (7 l; five pots per plant) filled with universal substrate and sand Despite its status and past conservation efforts, several traits of (70:30). The plants were cultivated in the open space, under natu- the reproductive biology of this species remain unknown. ral conditions (ambient temperature, humidity and natural light), Classical greenhouse experiments are excellent for implement- at the Botanical Garden of the Cagliari University, but watered three ing detailed studies of mating systems and inbreeding depression times a week. The third year (2013), the 86 surviving plants (belong- at successive reproductive stages (Alonso and Garcia-Sevilla, 2013). ing to 18 mother plants) were used to carry out this experiment. This is required to understand the potential advantages and disad- vantages of selfing in those species whose extensive manipulation 2.2. Ex situ phenology and floral biology in the field may be problematic or difficult (Alonso and Garcia- Sevilla, 2013). In this context, this work aims to provide new During the flowering season, observations of the open flowers information about the reproductive biology of D. morisianus in an of each plant were carried out once a day, during the flower’s lifes- ex situ experiment; in particular, the following aspects were inves- pan. These observations allowed us to detect the different stages tigated: (1) floral biology, (2) flowering phenology, (3) breeding during the flower’s lifespan. Each flower was marked with a univo- system and (4) inbreeding depression. cal code on the calyx using adhesive tape and a permanent marker. The following floral parameters were obtained: maximum flowering (considered to be the maximum number of open flowers per 2. Material and methods plant) and time to reach maximum flowering (number of days from the first open flower in the population to the day of the maxi- 2.1. Study species and plant materials mum flower count on each plant; Bishop and Schemske, 1998); flowering duration per plant and group of plants studied (in days); Dianthus morisianus Vals. (Caryophyllaceae) is a perennial char- flowering phenology, and flowering synchrony. The last parameter acterized by numerous woody stocks, erect stems and a basal is described as the number of days that the flowering of an individ- rosette with thin and linear leaves (Fig. 1A). It is a gynomonoecious ual overlaps with the flowering of every other plant (Augspurger, plant that presents hermaphroditic and, in low frequency, female 1983) and calculated following the formula: flowers. The stems bear terminal multi-flowered heads; the calyx is characterized by lanceolate teeth and the color of the corolla 1 1 X = e i j =/ i is pink. Petals present 6–8 teeth, rounded and irregularly lobed. − (n 1) fi Anthers measure 4.5 mm long, the ovary 7.5 mm long and

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